1. Field of the Invention
This invention relates to magnetic bubble memories and more particularly to magnetoresistive detectors for such bubbles.
2. Description of the Prior Art
Magnetic bubble memories are well known in the art. The most common detector for detecting magnetic bubbles in such a memory is an expansion detector of a type disclosed in A. H. Bobeck, F. J. Ciak and W. Strauss, U.S. Pat. No. 3,702,995, issued Nov. 14, 1972. That patent describes a detector which is defined by a column of chevron-shaped elements operative to expand a bubble along an axis lateral to that along which the bubble moves. Both bubble movement and expansion are due to a pattern of magnetic elements commonly composed of magnetically soft permalloy in response to a rotating in-plane magnetic field in a now-familiar manner.
That patent shows the chevron elements of a detector interlinked by permalloy connections between the apices of the elements and states that the interlinking elements can come at points other than the apices. Interlinking elements at alternate ends of successive elements leads to the longest magnetoresistive path and, supposedly, to the largest output signal corresponding to the passage of a bubble by the column of chevron elements in the detector stage.
By the same philosophy, the movement of one set of interlinking elements from one edge to the apices of the chevron elements shortens the magnetoresistive path and would be expected to produce a signal of limited amplitude and which would be relatively difficult and thus expensive to detect.